User Coordinate Systems

When you create entities in a drawing, they are located in relation to the drawing's underlying Cartesian coordinate system. The ELEVATION system variable specifies the distance from the xy-plane of the current coordinate system. If ELEVATION = 0 (zero), entities are created in the xy-plane of the current coordinate system.

Every drawing has a fixed coordinate system called the World Coordinate System (WCS).

You can also define arbitrary coordinate systems located anywhere in three-dimensional space. These are called user coordinate systems (UCS) and can be located anywhere in the WCS and oriented in any direction. You can create as many UCS as you want, saving or redefining them to help you construct three-dimensional entities. By defining a UCS within the WCS, you can simplify the creation of most three-dimensional entities into combinations of two-dimensional entities.

When you create a new drawing the WCS is the current coordinate system by default, which is indicated by the letter W in the UCS icon. When you display a drawing in plan view, you see the coordinate system icon from the top, with the z-axis directed straight toward you. When you display a three-dimensional drawing in a view other than plan view, the coordinate system icon changes to reflect your new viewpoint.

NOTE

You cannot delete or modify the WCS.

To help you keep your bearings in the current coordinate system, BricsCAD displays a coordinate system icon (UCS icon). The visible portions of the axes are the positive directions.

2D Wireframe visual style

WCS Top View

UCS Top View

WCS Isometric View

UCS Isometric View

Rendered Visual Styles

Three colors represent the three axes, making it easier for you to recognize the orientation in three-dimensional space:

The Plan View command restores the Plan view or Top view of the current UCS or WCS.

The UCSICON settings variable controls the display and location of the UCS icon:

Show icon :

Controls whether the icon shows or not.

at origin :

Controls the location of the UCS icon: if on, the icon indicates the origin point of the current coordinate system (UCS or WCS). However, if the origin is not within the viewport borders, the UCS icon moves to the corner of the viewport, as defined by the UCSICONPOS (UCS Icon Position) settings variable.When the at origin option is not checked, the icon always displays in the corner of the viewport defined by UCSICONPOS.

To move the origin of the current coordinate system

Type ucs at the command prompt.You are prompted: Specify origin of UCS or [Face/NAmed/Entity/Previous/View/X/Y/Z/Z Axis/Move/World] <World>:

4. Click one of the Planar UCS's buttons.The User Coordinate System dialog closes.

NOTES

If the UCSORTHO system variable is ON an orthographic UCS is restored automatically when the related orthographic view is restored by the -VIEW command or selected on the Look From control.An orthographic UCS has its origin at the WCS origin.

The UCSVP (UCS viewports) system variable controls whether the UCS in a viewport is fixed (UCSVP = ON) or changes to match the UCS in the current viewport (UCSVP = Off). As a result, in a multiple viewport drawing, the UCS of all viewports that have UCSVP = Off matches the orthographic UCS of the current viewport if UCSORTHO = On.

Using the Dynamic UCS

If the UCSICON system variable = 3 (On at Origin), the UCS icon displays in the selected face.

The dynamic UCS is oriented according to the edge by which the cursor 'entered' the hovered face, thus providing users a way to manipulate the orientation of the DUCS. The origin of the DUCS is set to the start point of this edge and the X-axis is chosen codirectional to the tangent at the start point of the edge.

Bottom

Left

Curved

Top

Right

3. (option) Hit the Shift key to lock the DUCS, which allows you to start drawing outside the highlighted face.Hit the Shift key again to unlock the DUCS.

4. Pick a point to start drawing.

5. When the drawing command concludes, the WCS or previously defined UCS is restored.